We received our IMU!Brian is busy making it talk to the Arduino board. Meanwhile, I have been working on the alignment code. The alignment proccess uses the IMU's sensors to determine its orientation (roll, pitch, and heading) while stationary. I spent the last few days writing code based upon this document. Sorry, it's not free. Based upon the equations given in the paper, I wrote a Kalman filter that iteratively converges to the true orientation while the IMU is stationary. I wrote the Kalman code in Matlab and created a Simulink model to provide the sensor inputs. But that is as far as I got. Apparently, the student version of Simulink has a limit of 300 blocks.So I spent all that time and was so excited to see this thing run, and I got nothing. I wanted to pitch my laptop off the balcony.So now I need to do a bunch of work to turn complicated sets of Simulink blocks into a single Matlab block just to get the number of blocks below 300. I have also asked for a quote to upgrade to a new version of Matlab/Simulink, but I already know that is out of my budget.I hope to upload some simulation results as soon as I get the code running.Tom
Read more…T3
Posted by Sami Finnila on April 13, 2009 at 9:00am
As a part of a paper (some school stuff) covering my NXT AutoPilot I went into details of choosing an airframe. I thought that this might be of intrest to you as well.Here is something to consider while choosing your airframe:
(, where F(i) is drag, P is required power, v is the required speed to keep the airframe aloft, m is the mass of the airframe, A is the wing area and k, rhoo, and C(v) we can assume to be constant.)From the equation we see that if the weight of our airframe doubles the needed power to keep it aloft gets multiplied by almost three: 2^(3/2))=2,818... Also if the wing area doubles we need only about 3/4 (actually about 0,7) of the power we needed before (assuming the coefficients k and C(v) are constant). This is, of course, based on idealized situations but it's probably something worth keeping in mind while choosing your airframe since the more power you consume the more expensive your set up gets and your flight times get shorter. You might also want to consider the following:
, where 'a' represents the scale (size coefficient) of the airframe (again a highly idealized situation). But if we combine this equation with the first equation we come to the conclusion that the smaller the airframe the better. If we, for example, choose to use a model half the size of some other airframe we are going to consume only about 1/10th of the power we would use with the bigger model (if we assume the wing area to be roughly 1/4th of the bigger airframe and the shape of the both airframes to be identical).You should note, however, that these calculations only take the power needed to stay aloft into consideration and if you carry a payload the weight of which doesn't vary with the size of the airframe you will probably have to resort to bigger airframes.
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How two Ardupilots died in one weekend.Yes I was so proud. I had a perfect working ardupilot. I was going to attach my just arrived Z sensor.Then Murphy law kicked in. When a friend was over I showed him my ardupilot. and the working.The positive power line of the lipo accu was not perfectly isolated and made contact with the back plane of the ardupilot.Yes it fried it. :-( . No swet I have a spare one). Solderd the headers tested the upload all fine. Now I needed to load the new firmware for the failsave. I dit this before and had some trouble but I managed. Now I really made a mistake. I forgot to power the arduino externally with the esc when I burned the hex and fuses and is not responding any more. So my attiny45 is gone now. So I just logged in the sparkfun site to backorder two new Ardupilots. And some xbee's end some other stuff.
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How to create a "realistic" UAV flight dynamic model of a popular UAV airframe (such as MutiplexEasyStar ) for simulation?
Is it possible to create a generic model such a way that the model can later be re-configured for different UAV airframes?
The model should be able to accurately approximate the next state (position, attitude, velocities and accelerations) of the UAV given its current state and control inputs (throttle, ailerons, rudder, elevator control values). That is, the model should tell me what will happen in dt (delta t, i.e. short time interval) time in the future if I apply a know set of control inputs.
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Waypoint tracking is one of the most sought-out features in an autopilot. Essentially it allows the end-user to program (generally via a map or an aerial picture) a path (composed of waypoints) that the UAV is commanded to track. When we started working on SLUGS it was clear that this would be the first high-level feature we would add.Today I am happy to report that it is fully working in software simulation and hardware-in-the-loop (HIL). You can read a bit more about it here and watch a couple of movies showing results from a Simulink software simulation and a full Hardware-in-the-Loop test.
Read more…3D Robotics
While we're waiting for the Atmega328 chips to come in so we can restart ArduPilot production (hopefully by the end of the month), I thought you'd be interested in this picture of ArduPilot being programmed and tested, which showed up in a Sparkfun post about their in-house production techniques. Here's the description:
"Thanks to Pete, our in house test bed master and proprietor of the "sneaky footprint", we use pogo pins for our test beds in production. "
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Has anyone achieved autonomous takeoff and landing with ArduPilot yet? If so can you share with everyone how you accomplished it. I have been wondering how to achieve this and what additional sensors / hardware will be required. Is it just a matter of setting way points and triggering certain tasks to take place at those way points for both take off and landing, or is there another way to accomplish this?
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Posted by Bryan Cuervo on April 12, 2009 at 8:46am
I posted an earlier blog with pictures on how I placed the avionics in an EasyGlider Pro for autonomous flight. I found out that was the easy part! Now I’m performing flight tests to hone in on the code mods for stable flight ( as Jordi states, the latest code is optimized for the EasyStar). My method has been:Fly and observe performance in autonomous mode – record observations – make code modifications on laptop – remove GPS and upload code – replace GPS – fly again. Laborious but also fun since physical computing yields immediate effects that you get to see.I’ve attached a table I made in Excel to organize my iterations and keep me on track. Maybe this will help others in the same situation. One mistake I made was getting in a hurry to go fly. I could have found out about the reversed servo throws and IR sensor placement by just walking the plane around on the ground and changing its attitude by hand. This would have avoided the “death spirals” I experienced on that first day of flying!Bryan
OdysseyThis is a unit for a full size plane, but it would be nice if the GCS could look something like that when it's done!! This unit also have a very impressive list of features. Wonder if one can use it as a GCS+AP and have only the sensors with Xbee on the plane.
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Hey everyone,I haven't been on the site in a while and I am amazed at what is/has come out of this community in the past 8 months.Anyway, I made a blimp last year for a class at RISD taught by Paul Badger. The blimp follows people. Its based around the arduino, a pyroelectric sensor, and an ultrasound sensor. The code is quite simple: it scans for heat (IR at ~ human frequency) and once it finds a maximum above threshold, it moves towards the location of heat and corrects for height.I started out with some mathematically complex programming but soon learned that very simple rules performed satisfactory. I don't plan on adding any more advanced controls or processes: its simple, stupid, and fun.A video of the blimp is here.also on the video is some other stuff I've done including a drawbot that draws in polar coordinates, and a bicycle powered record player (hah, not done).
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Posted by Robert Drone on April 11, 2009 at 7:18am
What does anyone think of this radio:http://www.nitroplanes.com/72waraco4chf.htmlWalkera Radio Control 4 Channel FM Transmitter Perfect for Helicopter and Airplane4 Channel R/C Set included, complete Left/ Right, Up/ Down Control ( RUDDER, AILERON, ELEVATOR AND THROTTLE. Suitable for Indoor / Outdoor / Backyard / Park ( 500 sqft area )Includes:One 4 Channel FM Transmitter w. Tx Battery holderOne ReceiverOne Crystal SetOne Receiver Battery Box w/ BEC connectorTwo 9 Gram ServosOne Switch HarnessOne Tx AntennaBattery HolderRequires: 8 AA batteriesRegular price: $99.95Sale price: $44.95It looks good to me and very affordable. What does every one else think?Link:http://www.nitroplanes.com/72waraco4chf.htmlRead more…
Well today I am verry close finishing my first plane with a autopilot.So it is time for some contribution to this fantastic site.First I like to thank Chris Anderson and Jordi for all the effort they made!!I really like what you have done so far!!!
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Posted by yuanzhenzong on April 11, 2009 at 12:59am
as an engineer worked for uav,I need variety of knowledge about the system.It includes composite material Aerodynamics,propultion,avinics,payload(op or ir sensor)and the communication.because the real enrienment of education in my country,I haven't get the valuable material about that,today find this page and find kinds of products and subsystems,thank you.
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Posted by Kyle Corbitt on April 10, 2009 at 7:30pm
Hey everyone, I would like to take this opportunity to post a screenshot of the groundstation I've just begun work on. I haven't gotten very far in the short time I've been working on it, but my goal is to release it around the same time as the upcoming ArduPilot Pro, which should have the ability to use a two-way digital radio for control. That gives me a good chunk of time for development and tuning.
I've put more time into playing around with different layouts than anything else so far, and I think I've settled on one that seems servicable. I would greatly appreciate it though if other community members (particularly those involved with ArduPilot Pro development) could let me know what you think of the direction I'm going... it would be much better to know sooner than later if I'm barking up the wrong tree!I should also mention that currently the "File" menu is set up as follows:"Load MissionSave Mission-------------Import KMLExport KML-------------Load PlaybackSave Playback-------------Exit"(there is nothing under "Settings" yet)Finally, for anyone interested in the code itself, I've been developing in Python using wxPython for the GUI elements.
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I've been having some problems intermittently with RF interference when flying my Nexstar EP. I always thought it was just some local interference which kicked on and off for whatever reason and that I needed to just do a range test before each flight.However, just today I decided to try a range test with & without Ardupilot installed. With Ardupilot I could only go about 200 feet away before i started getting pretty significant twitching of the servos. Without Ardupilot everything was still rock solid at 200+ feet. So it looks like the jumble of wires I had inside before won't work... are there any special precautions I can take besides just organizing wires and keeping Ardupilot as far from the receiver as possible? Is it important to keep Ardupilot away from the ESC as well? Does anyone have any home-made RF shield ideas?I also want to thank Chris & Jordi for making Ardupilot - not only a great autopilot but a really great place for beginners to start learning.
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Posted by Robert Drone on April 10, 2009 at 8:00am
Hi, I'm a bored teen living in south Georgia; so how's that different from any other teen? Well, I'm bored because what they teach us n school here is stuff I've known for a long time for the most part sooo I was looking around at airplanes online thinking about building a UAV and I came across this site after a while I got permission from my parents to use this site and here I am. I just posted some pictures of my custom airframe I am building and some electronics gear I could hack. I am a noob to real rc models (you know brushless motors and servos and stuff) the only real experience I have is the lego robotics system and messing with junked electonics and stuff. I was wondering if any one could answer the following questions:1. Has anyone launched an NXT or RCX using an all electric aircraft?2.Should I use the monster-truck rc unit to save money or buy a new one?(it is old so it is not proportional)3.Do you have to use a brushless and brand new battery?(could I use the one pictured)4.Could I build a magnetic sensor for the rcx or nxt?5. Does anyone have any comments questions or ideas for me?Here is a link to my pictures:
